Gate valves are used in fluid handling applications when a straight-line flow of fluid with minimum restriction is desired. A gate, or disc, engages a pair of opposed seals when the valve is in the closed position to shut off the straight-line flow. When the gate is lifted, configuring the valve in the open position, fluid is able to flow freely between the inlet and outlet ports of the valve. As designed, gate valves are typically operated in either the fully open or fully closed position.
In some cases, the opposed seals are metal, and the gate is either metal or non-metallic. As can be appreciated, the disadvantage of such metallic seal configurations is that they can result in substantial short term wear of the gate and/or seals.
In other cases, the opposed seals are elastomeric and the gate is metal. With such arrangements, the seals operate to provide a resilient seal against the gate. The problem with such elastomeric seal arrangements, however, is that the portion of the soft elastomeric material which engages the gate can abrade as the gate moves between the open and closed positions. As the gate cycles through the sleeve, it can rip off the nose, split the sleeve open, or cut chunks away so that eventually the valve leaks. Attempts have been made to reinforce the elastomeric seals, but providing too much rigidity/support for the nose can also accelerate wear of the seals.
Thus, there is a need for an improved reinforcement configuration for elastomeric seals used in gate valve applications. The configuration should provide a balance in stiffness and flexibility so that the resulting seal has an increased life expectancy as compared to current seals.